Question

Solve by substitution method :

$x+2y=-1and2x-3y=12$

Answer 1

Given equations are:

$$\begin{gathered} x+2y=-1............................\left(i\right) \\ 2x-3y=12...........................\left(ii\right) \end{gathered}$$

From equation $\left(i\right)$ we get $x=-2y-1$

Put value $x$ from equation (i) into equation (ii)

$$\begin{gathered} 2x-3y=12 \\ \Rightarrow 2\left(-2y-1\right)-3y=12 \\ \Rightarrow -4y-2-3y=12 \\ \Rightarrow -7y=14 \\ \Rightarrow y=\frac{14}{-7} \\ \Rightarrow y=-2 \end{gathered}$$

And

$$\begin{gathered} x=-2\times -2-1 \\ =4-1 \\ =3 \end{gathered}$$

Hence, The solution of the given equation is $x=3,y=-2$